Method for preferential selection of modes and gear with inertia effects for a hybrid powertrain system

ABSTRACT

A method for controlling a hybrid powertrain system selectively operative in one of a plurality of operating range states including an engine includes monitoring an operator torque request and a rotational speed of the output member, determining inertial effects of the transmissions, determining motor torque outputs from the electrical machines and an engine based upon the inertial effects, and selecting a preferred operating range state and a preferred input speed from the engine to the transmission based upon the operator torque request and the inertial effects.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/985,271 filed on Nov. 4, 2007 which is hereby incorporated herein byreference.

TECHNICAL FIELD

This disclosure pertains to control systems for hybrid powertrainsystems.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Known hybrid powertrain architectures include torque-generative devices,including internal combustion engines and electric machines, whichtransfer torque through a transmission device to an output member. Oneexemplary hybrid powertrain includes a two-mode, compound-split,electro-mechanical transmission which utilizes an input member forreceiving tractive torque from a prime mover power source, preferably aninternal combustion engine, and an output member. The output member canbe operatively connected to a driveline for a motor vehicle fortransferring tractive torque thereto. Electric machines, operative asmotors or generators, generate a torque input to the transmission,independently of a torque input from the internal combustion engine. Theelectric machines may transform vehicle kinetic energy, transferredthrough the vehicle driveline, to electrical energy that is storable inan electrical energy storage device. A control system monitors variousinputs from the vehicle and the operator and provides operationalcontrol of the hybrid powertrain, including controlling transmissionoperating state and gear shifting, controlling the torque-generativedevices, and regulating the electrical power interchange among theelectrical energy storage device and the electric machines to manageoutputs of the transmission, including torque and rotational speed.

SUMMARY

A method for controlling a hybrid powertrain system selectivelyoperative in one of a plurality of operating range states including anengine includes monitoring an operator torque request and a rotationalspeed of the output member, determining inertial effects of thetransmissions, determining motor torque outputs from the electricalmachines and an engine based upon the inertial effects, and selecting apreferred operating range state and a preferred input speed from theengine to the transmission based upon the operator torque request andthe inertial effects.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments will now be described, by way of example, withreference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of an exemplary powertrain, in accordancewith the present disclosure;

FIG. 2 is a schematic diagram of an exemplary architecture for a controlsystem and powertrain, in accordance with the present disclosure;

FIG. 3 illustrates a control system architecture for controlling andmanaging torque in a hybrid powertrain system, in accordance with thepresent disclosure;

FIG. 4 is a schematic flow diagram illustrating the strategicoptimization control scheme, in accordance with the present disclosure;

FIG. 5 is a schematic flow diagram illustrating several aspects of astrategic manager, in accordance with the present disclosure;

FIG. 6 is a schematic flow diagram illustrating the strategicoptimization scheme, in accordance with the present disclosure;

FIGS. 7-9 are schematic flow diagrams, in accordance with the presentdisclosure; and

FIG. 10 is a datagraph, in accordance with the present disclosure.

DETAILED DESCRIPTION

Referring now to the drawings, wherein the showings are for the purposeof illustrating certain exemplary embodiments only and not for thepurpose of limiting the same, FIGS. 1 and 2 depict an exemplaryelectro-mechanical hybrid powertrain system. The exemplaryelectro-mechanical hybrid powertrain system in accordance with thepresent disclosure is depicted in FIG. 1, comprising a two-mode,compound-split, electro-mechanical hybrid transmission 10 operativelyconnected to an engine 14 and torque generating machines comprisingfirst and second electric machines (‘MG-A’) 56 and (‘MG-B’) 72. Theengine 14 and first and second electric machines 56 and 72 each generatemechanical power which can be transferred to the transmission 10. Thepower generated by the engine 14 and the first and second electricmachines 56 and 72 and transferred to the transmission 10 is describedin terms of input and motor torques, referred to herein as T_(I), T_(A),and T_(B) respectively, and speed, referred to herein as N_(I), N_(A),and N_(B), respectively.

The exemplary engine 14 comprises a multi-cylinder internal combustionengine selectively operative in several states to transfer torque to thetransmission 10 via an input shaft 12, and can be either aspark-ignition or a compression-ignition engine. The engine 14 includesa crankshaft (not shown) operatively coupled to the input shaft 12 ofthe transmission 10. A rotational speed sensor 11 monitors rotationalspeed of the input shaft 12. Power output from the engine 14, comprisingrotational speed and engine torque, can differ from the input speedN_(I) and the input torque T_(I) to the transmission 10 due to placementof torque-consuming components on the input shaft 12 between the engine14 and the transmission 10, e.g., a hydraulic pump (not shown) and/or atorque management device (not shown).

The exemplary transmission 10 comprises three planetary-gear sets 24, 26and 28, and four selectively engageable torque-transferring devices,i.e., clutches C1 70, C2 62, C3 73, and C4 75. As used herein, clutchesrefer to any type of friction torque transfer device including single orcompound plate clutches or packs, band clutches, and brakes, forexample. A hydraulic control circuit 42, preferably controlled by atransmission control module (hereafter ‘TCM’) 17, is operative tocontrol clutch states. Clutches C2 62 and C4 75 preferably comprisehydraulically-applied rotating friction clutches. Clutches C1 70 and C373 preferably comprise hydraulically-controlled stationary devices thatcan be selectively grounded to a transmission case 68. Each of theclutches C1 70, C2 62, C3 73, and C4 75 is preferably hydraulicallyapplied, selectively receiving pressurized hydraulic fluid via thehydraulic control circuit 42.

The first and second electric machines 56 and 72 preferably comprisethree-phase AC machines, each including a stator (not shown) and a rotor(not shown), and respective resolvers 80 and 82. The motor stator foreach machine is grounded to an outer portion of the transmission case68, and includes a stator core with coiled electrical windings extendingtherefrom. The rotor for the first electric machine 56 is supported on ahub plate gear that is operatively attached to shaft 60 via the secondplanetary gear set 26. The rotor for the second electric machine 72 isfixedly attached to a sleeve shaft hub 66.

Each of the resolvers 80 and 82 preferably comprises a variablereluctance device including a resolver stator (not shown) and a resolverrotor (not shown). The resolvers 80 and 82 are appropriately positionedand assembled on respective ones of the first and second electricmachines 56 and 72. Stators of respective ones of the resolvers 80 and82 are operatively connected to one of the stators for the first andsecond electric machines 56 and 72. The resolver rotors are operativelyconnected to the rotor for the corresponding first and second electricmachines 56 and 72. Each of the resolvers 80 and 82 is signally andoperatively connected to a transmission power inverter control module(hereafter ‘TPIM’) 19, and each senses and monitors rotational positionof the resolver rotor relative to the resolver stator, thus monitoringrotational position of respective ones of first and second electricmachines 56 and 72. Additionally, the signals output from the resolvers80 and 82 are interpreted to provide the rotational speeds for first andsecond electric machines 56 and 72, i.e., N_(A) and N_(B), respectively.

The transmission 10 includes an output member 64, e.g. a shaft, which isoperably connected to a driveline 90 for a vehicle (not shown), toprovide output power to the driveline 90 that is transferred to vehiclewheels 93, one of which is shown in FIG. 1. The output power at theoutput member 64 is characterized in terms of an output rotational speedN_(O) and an output torque T_(O). A transmission output speed sensor 84monitors rotational speed and rotational direction of the output member64. Each of the vehicle wheels 93 is preferably equipped with a frictionbrake 94 and a sensor (not shown) adapted to monitor wheel speed, theoutput of which is monitored by a control module of a distributedcontrol module system described with respect to FIG. 2, to determinevehicle speed, and absolute and relative wheel speeds for brakingcontrol, traction control, and vehicle acceleration management.

The input torque from the engine 14 and the motor torques from the firstand second electric machines 56 and 72 (T_(I), T_(A), and T_(B)respectively) are generated as a result of energy conversion from fuelor electrical potential stored in an electrical energy storage device(hereafter ‘ESD’) 74. The ESD 74 is high voltage DC-coupled to the TPIM19 via DC transfer conductors 27. The transfer conductors 27 include acontactor switch 38. When the contactor switch 38 is closed, undernormal operation, electric current can flow between the ESD 74 and theTPIM 19. When the contactor switch 38 is opened electric current flowbetween the ESD 74 and the TPIM 19 is interrupted. The TPIM 19 transmitselectrical power to and from the first electric machine 56 by transferconductors 29, and the TPIM 19 similarly transmits electrical power toand from the second electric machine 72 by transfer conductors 31 tomeet the torque commands for the first and second electric machines 56and 72 in response to the motor torque commands T_(A) and T_(B).Electrical current is transmitted to and from the ESD 74 in accordancewith whether the ESD 74 is being charged or discharged.

The TPIM 19 includes the pair of power inverters (not shown) andrespective motor control modules (not shown) configured to receive themotor torque commands and control inverter states therefrom forproviding motor drive or regeneration functionality to meet thecommanded motor torques T_(A) and T_(B). The power inverters compriseknown complementary three-phase power electronics devices, and eachincludes a plurality of insulated gate bipolar transistors (not shown)for converting DC power from the ESD 74 to AC power for poweringrespective ones of the first and second electric machines 56 and 72, byswitching at high frequencies. The insulated gate bipolar transistorsform a switch mode power supply configured to receive control commands.There is typically one pair of insulated gate bipolar transistors foreach phase of each of the three-phase electric machines. States of theinsulated gate bipolar transistors are controlled to provide motor drivemechanical power generation or electric power regenerationfunctionality. The three-phase inverters receive or supply DC electricpower via DC transfer conductors 27 and transform it to or fromthree-phase AC power, which is conducted to or from the first and secondelectric machines 56 and 72 for operation as motors or generators viatransfer conductors 29 and 31 respectively.

FIG. 2 is a schematic block diagram of the distributed control modulesystem. The elements described hereinafter comprise a subset of anoverall vehicle control architecture, and provide coordinated systemcontrol of the exemplary hybrid powertrain described in FIG. 1. Thedistributed control module system synthesizes pertinent information andinputs, and executes algorithms to control various actuators to meetcontrol objectives, including objectives related to fuel economy,emissions, performance, drivability, and protection of hardware,including batteries of ESD 74 and the first and second electric machines56 and 72. The distributed control module system includes an enginecontrol module (hereafter ‘ECM’) 23, the TCM 17, a battery pack controlmodule (hereafter ‘BPCM’) 21, and the TPIM 19. A hybrid control module(hereafter ‘HCP’) 5 provides supervisory control and coordination of theECM 23, the TCM 17, the BPCM 21, and the TPIM 19. A user interface(‘UI’) 13 is operatively connected to a plurality of devices throughwhich a vehicle operator controls or directs operation of theelectro-mechanical hybrid powertrain system. The devices include anaccelerator pedal 113 (‘AP’), an operator brake pedal 112 (‘BP’), atransmission gear selector 114 (‘PRNDL’), and a vehicle speed cruisecontrol (not shown). The transmission gear selector 114 may have adiscrete number of operator-selectable positions, including therotational direction of the output member 64 to enable one of a forwardand a reverse direction.

The aforementioned control modules communicate with other controlmodules, sensors, and actuators via a local area network (hereafter‘LAN’) bus 6. The LAN bus 6 allows for structured communication ofstates of operating parameters and actuator command signals between thevarious control modules. The specific communication protocol utilized isapplication-specific. The LAN bus 6 and appropriate protocols providefor robust messaging and multi-control module interfacing between theaforementioned control modules, and other control modules providingfunctionality including e.g., antilock braking, traction control, andvehicle stability. Multiple communications buses may be used to improvecommunications speed and provide some level of signal redundancy andintegrity. Communication between individual control modules can also beeffected using a direct link, e.g., a serial peripheral interface(‘SPI’) bus (not shown).

The HCP 5 provides supervisory control of the hybrid powertrain, servingto coordinate operation of the ECM 23, TCM 17, TPIM 19, and BPCM 21.Based upon various input signals from the user interface 13 and thehybrid powertrain, including the ESD 74, the HCP 5 determines anoperator torque request, an output torque command, an engine inputtorque command, clutch torque(s) for the applied torque-transferclutches C1 70, C2 62, C3 73, C4 75 of the transmission 10, and themotor torque commands T_(A) and T_(B) for the first and second electricmachines 56 and 72.

The ECM 23 is operatively connected to the engine 14, and functions toacquire data from sensors and control actuators of the engine 14 over aplurality of discrete lines, shown for simplicity as an aggregatebi-directional interface cable 35. The ECM 23 receives the engine inputtorque command from the HCP 5. The ECM 23 determines the actual engineinput torque, T_(I), provided to the transmission 10 at that point intime based upon monitored engine speed and load, which is communicatedto the HCP 5. The ECM 23 monitors input from the rotational speed sensor11 to determine the engine input speed to the input shaft 12, whichtranslates to the transmission input speed, N_(I). The ECM 23 monitorsinputs from sensors (not shown) to determine states of other engineoperating parameters including, e.g., a manifold pressure, enginecoolant temperature, ambient air temperature, and ambient pressure. Theengine load can be determined, for example, from the manifold pressure,or alternatively, from monitoring operator input to the acceleratorpedal 113. The ECM 23 generates and communicates command signals tocontrol engine actuators, including, e.g., fuel injectors, ignitionmodules, and throttle control modules, none of which are shown.

The TCM 17 is operatively connected to the transmission 10 and monitorsinputs from sensors (not shown) to determine states of transmissionoperating parameters. The TCM 17 generates and communicates commandsignals to control the transmission 10, including controlling thehydraulic circuit 42. Inputs from the TCM 17 to the HCP 5 includeestimated clutch torques for each of the clutches, i.e., C1 70, C2 62,C3 73, and C4 75, and rotational output speed, N_(O), of the outputmember 64. Other actuators and sensors may be used to provide additionalinformation from the TCM 17 to the HCP 5 for control purposes. The TCM17 monitors inputs from pressure switches (not shown) and selectivelyactuates pressure control solenoids (not shown) and shift solenoids (notshown) of the hydraulic circuit 42 to selectively actuate the variousclutches C1 70, C2 62, C3 73, and C4 75 to achieve various transmissionoperating range states, as described hereinbelow.

The BPCM 21 is signally connected to sensors (not shown) to monitor theESD 74, including states of electrical current and voltage parameters,to provide information indicative of parametric states of the batteriesof the ESD 74 to the HCP 5. The parametric states of the batteriespreferably include battery state-of-charge, battery voltage, batterytemperature, and available battery power, referred to as a range P_(BAT)_(—) _(MIN) to P_(BAT) _(—) _(MAX).

A brake control module (hereafter ‘BrCM’) 22 is operatively connected tofriction brakes 94 on each of the vehicle wheels 93. The BrCM 22monitors the operator input to the brake pedal 112 and generates controlsignals to control the friction brakes 94 and sends a control signal tothe HCP 5 to operate the first and second electric machines 56 and 72based thereon.

Each of the control modules ECM 23, TCM 17, TPIM 19, BPCM 21, and BrCM22 is preferably a general-purpose digital computer comprising amicroprocessor or central processing unit, storage mediums comprisingread only memory (‘ROM’), random access memory (‘RAM’), electricallyprogrammable read only memory (‘EPROM’), a high speed clock, analog todigital (‘A/D’) and digital to analog (‘D/A’) circuitry, andinput/output circuitry and devices (‘I/O’) and appropriate signalconditioning and buffer circuitry. Each of the control modules has a setof control algorithms, comprising resident program instructions andcalibrations stored in one of the storage mediums and executed toprovide the respective functions of each computer. Information transferbetween the control modules is preferably accomplished using the LAN bus6 and serial peripheral interface buses. The control algorithms areexecuted during preset loop cycles such that each algorithm is executedat least once each loop cycle. Algorithms stored in the non-volatilememory devices are executed by one of the central processing units tomonitor inputs from the sensing devices and execute control anddiagnostic routines to control operation of the actuators, using presetcalibrations. Loop cycles are executed at regular intervals, for exampleeach 3.125, 6.25, 12.5, 25 and 100 milliseconds during ongoing operationof the hybrid powertrain. Alternatively, algorithms may be executed inresponse to the occurrence of an event.

The exemplary hybrid powertrain selectively operates in one of severalstates that can be described in terms of engine states comprising one ofan engine-on state (‘ON’) and an engine-off state (‘OFF’), andtransmission operating range states comprising a plurality of fixedgears and continuously variable operating modes, described withreference to Table 1, below.

TABLE 1 Engine Transmission Operating Applied Description State RangeState Clutches M1_Eng_Off OFF EVT Mode 1 C1 70 M1_Eng_On ON EVT Mode 1C1 70 G1 ON Fixed Gear Ratio 1 C1 70 C4 75 G2 ON Fixed Gear Ratio 2 C170 C2 62 M2_Eng_Off OFF EVT Mode 2 C2 62 M2_Eng_On ON EVT Mode 2 C2 62G3 ON Fixed Gear Ratio 3 C2 62 C4 75 G4 ON Fixed Gear Ratio 4 C2 62 C373

Each of the transmission operating range states is described in thetable and indicates which of the specific clutches C1 70, C2 62, C3 73,and C4 75 are applied for each of the operating range states. A firstcontinuously variable mode, i.e., EVT Mode 1, or M1, is selected byapplying clutch C1 70 only in order to “ground” the outer gear member ofthe third planetary gear set 28. The engine state can be one of ON(‘M1_Eng_On’) or OFF (‘M1_Eng_Off’). A second continuously variablemode, i.e., EVT Mode 2, or M2, is selected by applying clutch C2 62 onlyto connect the shaft 60 to the carrier of the third planetary gear set28. The engine state can be one of ON (‘M2_Eng_On’) or OFF(‘M2_Eng_Off’). For purposes of this description, when the engine stateis OFF, the engine input speed is equal to zero revolutions per minute(‘RPM’), i.e., the engine crankshaft is not rotating. A fixed gearoperation provides a fixed ratio operation of input-to-output speed ofthe transmission 10, i.e., N_(I)/N_(O). A first fixed gear operation(‘G1’) is selected by applying clutches C1 70 and C4 75. A second fixedgear operation (‘G2’) is selected by applying clutches C1 70 and C2 62.A third fixed gear operation (‘G3’) is selected by applying clutches C262 and C4 75. A fourth fixed gear operation (‘G4’) is selected byapplying clutches C2 62 and C3 73. The fixed ratio operation ofinput-to-output speed increases with increased fixed gear operation dueto decreased gear ratios in the planetary gears 24, 26, and 28. Therotational speeds of the first and second electric machines 56 and 72,N_(A) and N_(B) respectively, are dependent on internal rotation of themechanism as defined by the clutching and are proportional to the inputspeed measured at the input shaft 12.

In response to operator input via the accelerator pedal 113 and brakepedal 112 as captured by the user interface 13, the HCP 5 and one ormore of the other control modules determine torque commands to controlthe torque generative devices comprising the engine 14 and the first andsecond electric machines 56 and 72 to meet the operator torque requestat the output member 64 and transferred to the driveline 90. Based uponinput signals from the user interface 13 and the hybrid powertrainincluding the ESD 74, the HCP 5 determines the operator torque request,a commanded output torque from the transmission 10 to the driveline 90,the input torque from the engine 14, clutch torques for thetorque-transfer clutches C1 70, C2 62, C3 73, C4 75 of the transmission10; and the motor torques for the first and second electric machines 56and 72, respectively, as is described hereinbelow.

Final vehicle acceleration can be affected by other factors including,e.g., road load, road grade, and vehicle mass. The engine state and thetransmission operating range state are determined based upon operatingcharacteristics of the hybrid powertrain. This includes the operatortorque request communicated through the accelerator pedal 113 and brakepedal 112 to the user interface 13 as previously described. Thetransmission operating range state and the engine state may bepredicated on a hybrid powertrain torque demand caused by a command tooperate the first and second electric machines 56 and 72 in anelectrical energy generating mode or in a torque generating mode. Thetransmission operating range state and the engine state can bedetermined by an optimization algorithm or routine which determinesoptimum system efficiency based upon operator demand for power, batterystate of charge, and energy efficiencies of the engine 14 and the firstand second electric machines 56 and 72. The control system managestorque inputs from the engine 14 and the first and second electricmachines 56 and 72 based upon an outcome of the executed optimizationroutine, and system efficiencies are optimized thereby, to manage fueleconomy and battery charging. Furthermore, operation can be determinedbased upon a fault in a component or system. The HCP 5 monitors thetorque-generative devices, and determines the power output from thetransmission 10 at output member 64 that is required to meet theoperator torque request while meeting other powertrain operatingdemands, e.g., charging the ESD 74. As should be apparent from thedescription above, the ESD 74 and the first and second electric machines56 and 72 are electrically-operatively coupled for power flowtherebetween. Furthermore, the engine 14, the first and second electricmachines 56 and 72, and the electro-mechanical transmission 10 aremechanically-operatively coupled to transfer power therebetween togenerate a power flow to the output member 64.

FIG. 3 shows a control system architecture for controlling and managingsignal flow in a hybrid powertrain system having multiple torquegenerative devices, described hereinbelow with reference to the hybridpowertrain system of FIGS. 1 and 2, and residing in the aforementionedcontrol modules in the form of executable algorithms and calibrations.The control system architecture is applicable to alternative hybridpowertrain systems having multiple torque generative devices, including,e.g., a hybrid powertrain system having an engine and a single electricmachine, a hybrid powertrain system having an engine and multipleelectric machines. Alternatively, the hybrid powertrain system canutilize non-electric torque-generative machines and energy storagesystems, e.g., hydraulic-mechanical hybrid transmissions (not shown).

In operation, the operator inputs to the accelerator pedal 113 and thebrake pedal 112 are monitored to determine the operator torque request.The operator inputs to the accelerator pedal 113 and the brake pedal 112comprise individually determinable operator torque request inputsincluding an immediate accelerator output torque request (‘Output TorqueRequest Accel Immed’), a predicted accelerator output torque request(‘Output Torque Request Accel Prdtd’), an immediate brake output torquerequest (‘Output Torque Request Brake Immed’), a predicted brake outputtorque request (‘Output Torque Request Brake Prdtd’) and an axle torqueresponse type (‘Axle Torque Response Type’). As used herein, the term‘accelerator’ refers to an operator request for forward propulsionpreferably resulting in increasing vehicle speed over the presentvehicle speed, when the operator selected position of the transmissiongear selector 114 commands operation of the vehicle in the forwarddirection. The terms ‘deceleration’ and ‘brake’ refer to an operatorrequest preferably resulting in decreasing vehicle speed from thepresent vehicle speed. The immediate accelerator output torque request,the predicted accelerator output torque request, the immediate brakeoutput torque request, the predicted brake output torque request, andthe axle torque response type are individual inputs to the controlsystem. Additionally, operation of the engine 14 and the transmission 10are monitored to determine the input speed (‘Ni’) and the output speed(‘No’). The immediate accelerator output torque request is determinedbased upon a presently occurring operator input to the accelerator pedal113, and comprises a request to generate an immediate output torque atthe output member 64 preferably to accelerate the vehicle. The predictedaccelerator output torque request is determined based upon the operatorinput to the accelerator pedal 113 and comprises an optimum or preferredoutput torque at the output member 64. The predicted accelerator outputtorque request is preferably equal to the immediate accelerator outputtorque request during normal operating conditions, e.g., when any one ofantilock braking, traction control, or vehicle stability is not beingcommanded. When any one of antilock braking, traction control or vehiclestability is being commanded the predicted accelerator output torquerequest remains the preferred output torque with the immediateaccelerator output torque request being decreased in response to outputtorque commands related to the antilock braking, traction control, orvehicle stability control.

The immediate brake output torque request is determined based upon apresently occurring operator input to the brake pedal 112, and comprisesa request to generate an immediate output torque at the output member 64to effect a reactive torque with the driveline 90 which preferablydecelerates the vehicle. The predicted brake output torque requestcomprises an optimum or preferred brake output torque at the outputmember 64 in response to an operator input to the brake pedal 112subject to a maximum brake output torque generated at the output member64 allowable regardless of the operator input to the brake pedal 112. Inone embodiment the maximum brake output torque generated at the outputmember 64 is limited to −0.2 g. The predicted brake output torquerequest can be phased out to zero when vehicle speed approaches zeroregardless of the operator input to the brake pedal 112. When commandedby the operator, there can be operating conditions under which thepredicted brake output torque request is set to zero, e.g., when theoperator setting to the transmission gear selector 114 is set to areverse gear, and when a transfer case (not shown) is set to afour-wheel drive low range.

A strategic control scheme (‘Strategic Control’) 310 determines apreferred input speed (‘Ni_Des’) and a preferred engine state andtransmission operating range state (‘Hybrid Range State Des’) based uponthe output speed and the operator torque request and based upon otheroperating parameters of the hybrid powertrain, including battery powerlimits and response limits of the engine 14, the transmission 10, andthe first and second electric machines 56 and 72. The predictedaccelerator output torque request and the predicted brake output torquerequest are input to the strategic control scheme 310. The strategiccontrol scheme 310 is preferably executed by the HCP 5 during each 100ms loop cycle and each 25 ms loop cycle. The desired operating rangestate for the transmission 10 and the desired input speed from theengine 14 to the transmission 10 are inputs to the shift execution andengine start/stop control scheme 320.

The shift execution and engine start/stop control scheme 320 commandschanges in the transmission operation (‘Transmission Commands’)including changing the operating range state based upon the inputs andoperation of the powertrain system. This includes commanding executionof a change in the transmission operating range state if the preferredoperating range state is different from the present operating rangestate by commanding changes in application of one or more of theclutches C1 70, C2 62, C3 73, and C4 75 and other transmission commands.The present operating range state (‘Hybrid Range State Actual’) and aninput speed profile (‘Ni_Prof’) can be determined. The input speedprofile is an estimate of an upcoming input speed and preferablycomprises a scalar parametric value that is a targeted input speed forthe forthcoming loop cycle. The engine operating commands and theoperator torque request are based upon the input speed profile during atransition in the operating range state of the transmission.

A tactical control scheme (‘Tactical Control and Operation’) 330 isexecuted during one of the control loop cycles to determine enginecommands (‘Engine Commands’) for operating the engine 14, including apreferred input torque from the engine 14 to the transmission 10 basedupon the output speed, the input speed, and the operator torque requestcomprising the immediate accelerator output torque request, thepredicted accelerator output torque request, the immediate brake outputtorque request, the predicted brake output torque request, the axletorque response type, and the present operating range state for thetransmission. The engine commands also include engine states includingone of an all-cylinder operating state and a cylinder deactivationoperating state wherein a portion of the engine cylinders aredeactivated and unfueled, and engine states including one of a fueledstate and a fuel cutoff state. An engine command comprising thepreferred input torque of the engine 14 and the present input torque(‘Ti’) reacting between the engine 14 and the input member 12 arepreferably determined in the ECM 23. Clutch torques (‘Tcl’) for each ofthe clutches C1 70, C2 62, C3 73, and C4 75, including the presentlyapplied clutches and the non-applied clutches are estimated, preferablyin the TCM 17.

An output and motor torque determination scheme (‘Output and MotorTorque Determination’) 340 is executed to determine the preferred outputtorque from the powertrain (‘To_cmd’). This includes determining motortorque commands (‘T_(A)’, ‘T_(B)’) to transfer a net commanded outputtorque to the output member 64 of the transmission 10 that meets theoperator torque request, by controlling the first and second electricmachines 56 and 72 in this embodiment. The immediate accelerator outputtorque request, the immediate brake output torque request, the presentinput torque from the engine 14 and the estimated applied clutchtorque(s), the present operating range state of the transmission 10, theinput speed, the input speed profile, and the axle torque response typeare inputs. The output and motor torque determination scheme 340executes to determine the motor torque commands during each iteration ofone of the loop cycles. The output and motor torque determination scheme340 includes algorithmic code which is regularly executed during the6.25 ms and 12.5 ms loop cycles to determine the preferred motor torquecommands.

The hybrid powertrain is controlled to transfer the output torque to theoutput member 64 to react with the driveline 90 to generate tractivetorque at wheel(s) 93 to forwardly propel the vehicle in response to theoperator input to the accelerator pedal 113 when the operator selectedposition of the transmission gear selector 114 commands operation of thevehicle in the forward direction. Similarly, the hybrid powertrain iscontrolled to transfer the output torque to the output member 64 toreact with the driveline 90 to generate tractive torque at wheel(s) 93to propel the vehicle in a reverse direction in response to the operatorinput to the accelerator pedal 113 when the operator selected positionof the transmission gear selector 114 commands operation of the vehiclein the reverse direction. Preferably, propelling the vehicle results invehicle acceleration so long as the output torque is sufficient toovercome external loads on the vehicle, e.g., due to road grade,aerodynamic loads, and other loads.

For the continuously variable modes, i.e., M1 or M2, the speedrelationship between first and second electric machines 56 and 72, theinput speed N_(I) and the output speed N_(O) is defined as shown in theequation below:

$\begin{matrix}{\begin{bmatrix}N_{A} \\N_{B}\end{bmatrix} = {\left\lbrack A_{1} \right\rbrack \begin{bmatrix}N_{I} \\N_{O}\end{bmatrix}}} & \lbrack 1\rbrack\end{matrix}$

wherein N_(I) comprises the input speed from the engine 14, N_(O) is thetransmission output speed, N_(A) and N_(B) are the operating speeds forfirst and second electric machines 56 and 72, and A₁ is a 2×2 matrix ofparametric values based upon hardware gear and shaft interconnectionsdetermined for the specific application, and for the specific operatingrange state, i.e., M1 or M2.

The torque relationship between first and second electric machines 56and 72, the input speed N_(I), the output speed N_(O), input torque, andmotor torque is defined as:

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B}\end{bmatrix} = {{\begin{bmatrix}a_{11} & a_{12} \\a_{21} & a_{22}\end{bmatrix}\begin{bmatrix}T_{I} \\T_{O}\end{bmatrix}} + {\begin{bmatrix}b_{11} & b_{12} \\b_{21} & b_{22}\end{bmatrix}\begin{bmatrix}N_{I} \\N_{O}\end{bmatrix}}}} & \lbrack 2\rbrack\end{matrix}$

wherein T_(I) is the input torque from the engine 14, T_(O) is thetransmission output torque, T_(A) and T_(B) are the motor torques forfirst and second electric machines 56 and 72 and a₁₁, a₁₂, a₂₁, a₂₂,b₁₁, b₁₂, b₂₁, and b₂₂ are scalar values of known parametric valuesbased upon hardware gear and shaft interconnections determined for thespecific application and for the specific continuously variableoperating range state, i.e., M1 or M2.

For the fixed gear operating range states, i.e., G1, G2, G3 and G4 inone embodiment, the speed relationship between the first and secondelectric machines 56 and 72, the engine input speed N_(I) and thetransmission output speed N_(O) is defined as shown in the equationbelow:

$\begin{matrix}{\begin{bmatrix}N_{I} \\N_{A} \\N_{B}\end{bmatrix} = {\left\lbrack B_{1} \right\rbrack*N_{O}}} & \lbrack 3\rbrack\end{matrix}$

wherein N_(I) comprises the input speed from engine 14, N_(O) is thetransmission output speed, N_(A) and N_(B) are the operating speeds forfirst and second electric machines 56 and 72, and B_(I) is a 1×3 matrixof known parametric values based upon hardware gear and shaftinterconnections determined for the specific application, and for thespecific operating range state. In this application, when thetransmission output speed, N_(O) is known, N_(I) for the engine 14 andN_(A) and N_(B) can be determined.

The torque relationships between first and second electric machines 56and 72, input torque, and motor torque are as defined in Eq. 4 below:

$\begin{matrix}{T_{O} = {\begin{bmatrix}a & b & c & d & e\end{bmatrix}*\begin{bmatrix}T_{I} \\T_{A} \\T_{B} \\N_{i} \\N_{o}\end{bmatrix}}} & \lbrack 4\rbrack\end{matrix}$

wherein T_(I) is the input torque from engine 14, T_(O) is thetransmission output torque, i.e., the requested output torque, T_(O)_(—) _(REQ), T_(A) and T_(B) are the motor torques for first and secondelectric machines 56 and 72, a, b, c, d, and e are known parametricvalues based upon hardware gear and shaft interconnections determinedfor the specific application, and for the specific fixed gear operatingranges state.

The torque relationships given in Eqs. 2 and 4 do not compensate forinertial effects within the hybrid powertrain. To compensate for theinertial effects, the rotational acceleration of the input member 12 andthe output member 56 are included in Eq. 2 for the mode operating rangestates. Including the rotational acceleration terms the torquerelationship between first and second electric machines 56 and 72, theinput speed N_(I), the output speed N_(O), the input torque, and motortorques T_(A) and T_(B) is defined as:

$\begin{matrix}{\begin{bmatrix}T_{A} \\T_{B}\end{bmatrix} = {{\begin{bmatrix}a_{11} & a_{12} \\a_{21} & a_{22}\end{bmatrix}\begin{bmatrix}T_{I} \\T_{O}\end{bmatrix}} + {\begin{bmatrix}b_{11} & b_{12} \\b_{21} & b_{22}\end{bmatrix}\begin{bmatrix}N_{I} \\N_{O}\end{bmatrix}} + {\begin{bmatrix}c_{11} & c_{12} \\c_{21} & c_{22}\end{bmatrix}\overset{.}{\begin{bmatrix}N_{I} \\{\overset{.}{N}}_{O}\end{bmatrix}}}}} & \lbrack 5\rbrack\end{matrix}$

wherein

-   -   {dot over (N)}_(I) represents acceleration of the input member        12,    -   {dot over (N)}_(O) represents acceleration of output member 64,        and    -   a₁₁, a₁₂, a₂₁, a₂₂, b₁₁, b₁₂, b₂₁, b₂₂ c₁₁, c₁₂, c₂₁, and c₂₂        are known parametric values based upon hardware gear and shaft        interconnections determined for the specific application and for        the specific operating range state, i.e., M1 or M2.

For the fixed gear operating ranges states, compensating for theinertial effects comprises including the rotational acceleration of theinput member 12 in Eq. 4. Including the rotational acceleration of theinput member 12 the torque relationships between first and secondelectric machines 56 and 72, input torque, and output torque are definedas:

$\begin{matrix}{T_{O} = {\begin{bmatrix}a & b & c & d & e & f\end{bmatrix}*\begin{bmatrix}T_{I} \\T_{A} \\T_{B} \\N_{i} \\N_{o} \\{\overset{.}{N}}_{I}\end{bmatrix}}} & \lbrack 6\rbrack\end{matrix}$

wherein {dot over (N)}_(I) represents acceleration of the input member12, and a, b, c, d, e, and f are known parametric values based uponhardware gear and shaft interconnections determined for the specificapplication, and for the specific operating range state.

FIG. 4 details signal flow in the strategic optimization control scheme310, which includes a strategic manager 220, an operating range stateanalyzer 260, and a state stabilization and arbitration block 280 todetermine the preferred input speed (‘Ni_Des’) and the preferredtransmission operating range state (‘Hybrid Range State Des’). Thestrategic manager (‘Strategic Manager’) 220 monitors the output speedN_(O), the predicted accelerator output torque request (‘Output TorqueRequest Accel Prdtd’), the predicted brake output torque request(‘Output Torque Request Brake Prdtd’), and available battery powerP_(BAT) _(—) _(MIN) to P_(BAT) _(—) _(MAX). The strategic manager 220determines which of the transmission operating range states areallowable, and determines output torque requests comprising a strategicaccelerator output torque request (‘Output Torque Request AccelStrategic’) and a strategic net output torque request (‘Output TorqueRequest Net Strategic’), all of which are input the operating rangestate analyzer 260 along with system inputs (‘System Inputs’) and powercost inputs (‘Power Cost Inputs’). The operating range state analyzer260 generates a preferred power cost (‘P*cost’) and associated inputspeed (‘N*i’) for each of the allowable operating range states basedupon the operator torque requests, the system inputs, the availablebattery power and the power cost inputs. The preferred power costs andassociated input speeds for the allowable operating range states areinput to the state stabilization and arbitration block 280 which selectsthe preferred operating range state and preferred input speed basedthereon.

FIG. 5 shows a functional block diagram detailing an operation of thestrategic manager 220. Within the strategic manager 220 are an inputacceleration algorithm (‘Calc Nidot (Modes)’) (221), a torque offsetalgorithm (‘Precalc TrqOffsets’) (222), and a strategic manageralgorithm (223). Inputs to the strategic manager algorithm include thepredicted accelerator output torque request (‘Output Torque RequestAccel Prdtd’), the predicted brake output torque request (‘Output TorqueRequest Brake Prdtd’), and the output speed (‘N_(O)’). The strategicmanager algorithm 223 determines a strategic output speed, the strategictorque request, and a rotational output acceleration of the outputmember 64. The input acceleration algorithm 221 inputs the strategicoutput speed (‘No Strategic’), the strategic torque request (‘To ReqStrategic’), and the rotational output acceleration (‘Nodot’). The inputacceleration algorithm 221 determines a rotational input acceleration(‘Nidot’) of the input member 12 for the continuously variable modes M1and M2. The torque offset algorithm 222 determines a torque offset foreach of the first and second electrical machines 56 and 72 (‘Ta offset’and ‘Tb offset’) for operating in one of the continuously variable modesand an output torque offset for the operating in one of the fixed gears(‘To offset’). The torque offsets are preferably determined in thestrategic manager 220 for increased computational efficiency. The torqueoffsets are output to the operating range state analyzer 260 asdescribed hereinbelow.

Preferably, the strategic output speed comprises a predicted outputspeed occurring at a future time instant. One method for determining thepredicted output speed comprises determining a time-based derivative ofthe monitored output speed No, multiplying the resultant with an elapsedtime from the present to the future time instant and adding theresultant to the monitored output speed No. The strategic torque requestis preferably a predicted operator torque request for a future timeinstant and is preferably based upon the predicted accelerator outputtorque request. The rotational output acceleration is preferablydetermined based upon the monitored output speed. The rotational outputacceleration can be determined by calculating a time-based derivative ofthe output speed N_(O) and adding the resultant to the monitored outputspeed No.

Preferably, for efficient implementation of Eq. 6 above and for the modeoperating range states M1 and M2, motor torque offsets are determinedfor each of the first and second electrical machines 56 and 72. Themotor torque offsets are determined based upon the rotational outputacceleration, the rotational input acceleration, and the strategicoutput speed. The torque offset for the first electrical machine 56 isdetermined based on the following equation:

T _(A) _(—) _(OFFSET) =b ₁₂ N _(O) +c ₁₁ {dot over (N)} _(I) +c ₁₂ {dotover (N)} _(O)  [7]

wherein

-   -   N_(O) represents output speed,    -   {dot over (N)}_(I) represents input acceleration,    -   {dot over (N)}_(O) represents output acceleration, and    -   b₁₂, c₁₁, and c₁₂ represent known parametric values based upon        hardware gear and shaft interconnections determined for the        specific application, and for the specific operating range        state.

The torque offset for the second electrical machine 72 is determinedbased on the following equation:

T _(B) _(—) _(OFFSET) =b ₂₂ N _(O) +c ₂₁ {dot over (N)} _(I) +c ₂₂ {dotover (N)} _(O)  [8]

wherein

-   -   N_(O) represents output speed,    -   {dot over (N)}_(I) represents input acceleration,    -   {dot over (N)}_(O) represents output acceleration, and    -   b₂₂, c₂₁, and c₂₂ represent known parametric values based upon        hardware gear and shaft interconnections determined for the        specific application, and for the specific operating range        state.

Preferably, for efficient implementation of Eq. 6 above and for thefixed gear operating range states, an output torque offset isdetermined. The torque offset is determined based upon the rotationaloutput acceleration, the strategic output speed, and the input speedN_(I). The output torque offset is determined based on the followingequation:

T _(O)Offset=dN _(I) +eN _(O) +f{dot over (N)} _(I)  [9]

wherein

-   -   d, e, and f represent known parametric values based upon        hardware gear and shaft interconnections determined for the        specific application, and for the specific operating range        state.

FIG. 6 shows the operating range state analyzer 260. The operating rangestate analyzer 260 executes searches in each candidate operating rangestate comprising the allowable ones of the operating range states,including M1 (262), M2 (264), G1 (270), G2 (272), G3 (274), and G4 (276)to determine preferred operation of the torque actuators, i.e., theengine 14 and the first and second electric machines 56 and 72 in thisembodiment. The preferred operation preferably comprises a minimum powercost for operating the hybrid powertrain system and an associated engineinput for operating in the candidate operating range state in responseto the operator torque request. The associated engine input comprises atleast one of a preferred engine input speed (‘Ni*’), a preferred engineinput power (‘Pi*’), and a preferred engine input torque (‘Ti*’) that isresponsive to and preferably meets the operator torque request. Theoperating range state analyzer 260 evaluates M1-Engine Off (264) andM2-Engine Off (266) to determine a preferred cost (‘P*cost’) foroperating the powertrain system responsive to and preferably meeting theoperator torque request when the engine 14 is in the engine-off state.

FIG. 7 schematically shows signal flow for the 1-dimension search scheme610. A range of one controllable input, in this embodiment comprisingminimum and maximum input torques (‘TiMin/Max’), is input to a 1-Dsearch engine 415. The 1-D search engine 415 iteratively generatescandidate input torques (‘Ti(j)’) which range between the minimum andmaximum input torques, each which is input to an optimization function(‘Opt To/Ta/Tb’) 440, for n search iterations. Other inputs to theoptimization function 440 include system inputs preferably compriseparametric states for battery power, clutch torques, electric motoroperation, transmission and engine operation, the specific operatingrange state and the operator torque request. The optimization function440 determines transmission operation comprising an output torque, motortorques, and associated battery powers (‘To(j), Ta(j), Tb(j), Pbat(j),Pa(j), Pb(j)’) associated with the candidate input torque based upon thesystem inputs in response to the operator torque request for thecandidate operating range state.

FIG. 8 shows the preferred operation in each of continuously variablemodes M1 and M2 executed in blocks 262 and 264 of the operating rangestate analyzer 260. This includes executing a 2-dimensional searchscheme 620, shown with reference to FIGS. 7 and 9, in conjunction withexecuting a 1-dimensional search using the 1-dimensional search scheme610 based upon a previously determined input speed which can bearbitrated (‘Input Speed Stabilization and Arbitration’) 615 todetermine preferred costs (‘P*cost’) and associated preferred inputspeeds (‘N*i’) for the operating range states. As described withreference to FIG. 8, the 2-dimensional search scheme 620 determines a afirst preferred cost (‘2D P*cost’) and an associated first preferredinput speed (‘2D N*I’). The first preferred input speed is input to the2-dimensional search scheme 620 and to an adder 612. The adder 612 sumsthe first preferred input speed and a time-rate change in the inputspeed (‘N_(I) _(—) _(DOT)’) multiplied by a predetermined time period(‘dt’). The resultant is input to a switch 605 along with the firstpreferred input speed determined by the 2-dimensional search scheme 620.The switch 605 is controlled to input either the resultant from theadder 612 or the preferred input speed determined by the 2-dimensionalsearch scheme 620 into the 1-dimensional search scheme 610. The switch605 is controlled to input the preferred input speed determined by the2-dimensional search scheme 620 into the 1-dimensional search scheme 610(as shown) when the powertrain system is operating in a regenerativebraking mode, e.g., when the operator torque request includes a requestto generate an immediate output torque at the output member 64 to effecta reactive torque with the driveline 90 which preferably decelerates thevehicle. The switch 605 is controlled to a second position (not shown)to input the resultant from the adder 612 when the operator torquerequest does not include regenerative braking. The 1-dimensional searchscheme 610 is executed to determine a second preferred cost (‘1DP*cost’) using the 1-dimensional search scheme 610, which is input tothe input speed stabilization and arbitration block 615 to select afinal preferred cost and associated preferred input speed.

FIG. 9 schematically shows signal flow for the 2-dimension search scheme620. Ranges of two controllable inputs, in this embodiment comprisingminimum and maximum input speeds (‘NiMin/Max’) and minimum and maximuminput powers (‘PiMin/Max’) are input to a 2-D search engine 410. Inanother embodiment, the two controllable inputs can comprise minimum andmaximum input speeds and minimum and maximum input torques. The 2-Dsearch engine 410 iteratively generates candidate input speeds (‘Ni(j)’)and candidate input powers (‘Pi(j)’) which range between the minimum andmaximum input speeds and powers. The candidate input power is preferablyconverted to a candidate input torque (‘Ti(j)’) (412). Each candidateinput speed (‘Ni(j)’) and candidate input torque (‘Ti(j)’) are input toan optimization function (‘Opt To/Ta/Tb’) 440, for n search iterations.Other inputs to the optimization function 440 include system inputspreferably comprising parametric states for battery power, clutchtorques, electric motor operation, transmission and engine operation,the specific operating range state and the operator torque request. Theoptimization function 440 determines transmission operation comprisingan output torque, motor torques, and associated battery powers (‘To(j),Ta(j), Tb(j), Pbat(j), Pa(j), Pb(j)’) associated with the candidateinput power and candidate input speed based upon the system inputs andthe operating torque request for the candidate operating range state.

Additional inputs into the optimization function 440 include the motortorque offsets and the output torque offset. For the fixed gearoperating ranges states, the optimization function 440 determines theoutput torque for each candidate input speeds Ni(j) and candidate inputtorque Ti(j) based upon the output torque offset determined in thestrategic manager 220, motor torques, and known parametric values basedupon hardware gear and shaft interconnections determined for thespecific application, and for the specific operating range state. Theoutput torque can be determined based upon the following equation:

$\begin{matrix}{{T_{O}(j)} - {\begin{bmatrix}a & b & c\end{bmatrix}\begin{bmatrix}{T_{I}(j)} \\{T_{A}(j)} \\{T_{B}(j)}\end{bmatrix}} + {T_{o}\mspace{14mu} {Offset}}} & \lbrack 10\rbrack\end{matrix}$

wherein

-   -   T_(A)(j) represents motor torque for the first electric machine        56,    -   T_(B)(j) represents motor torque for the second electric machine        72,    -   T_(I)(j) represents engine input torque to the transmission 10,    -   T_(O)(j) is the output torque out of the transmission 10, and    -   a, b, and c are known parametric values based upon hardware gear        and shaft interconnections determined for the specific        application and for the specific operating range state.

For the continuously variable mode operating range states M1 and M2, theoptimization function 440 determines the output torque and motor torquesfor each candidate input speeds Ni(j) and candidate input powers Pi(j)based upon the motor torque offsets determined in the strategic manager220, the candidate input torque Ti(j), output torque, candidate inputspeed Ni(j), and known parametric values based upon hardware gear andshaft interconnections determined for the specific application, and forthe specific operating range state. The output torque and motor torquesare determined based upon the following equation:

$\begin{matrix}{\begin{bmatrix}{T_{A}(j)} \\{T_{B}(j)}\end{bmatrix} = {{\begin{bmatrix}a_{11} & a_{12} \\a_{21} & a_{22}\end{bmatrix}\begin{bmatrix}{T_{I}(j)} \\{T_{O}(j)}\end{bmatrix}} + {\begin{bmatrix}{b_{11} \cdot {N_{I}(j)}} \\{b_{21} \cdot {N_{I}(j)}}\end{bmatrix}\begin{bmatrix}{T_{A}\mspace{14mu} {Offset}} \\{T_{B}\mspace{14mu} {Offset}}\end{bmatrix}}}} & \lbrack 11\rbrack\end{matrix}$

wherein

-   -   T_(A)(j) represents motor torque for the first electric machine        56,    -   T_(B)(j) represents motor torque for the second electric machine        72,    -   T_(I)(j) represents engine input torque to the transmission 10,    -   T_(O)(j) is the output torque out of the transmission 10,    -   N_(I)(j) represents input speed, and    -   a₁₁, a₁₂, a₂₁, a₂₂, b₁₁, b₂₁ are known parametric values based        upon hardware gear and shaft interconnections determined for the        specific application and for the specific operating range state.

The output torque (‘T_(O)(j)’), motor torques (‘T_(A)(j)’) and(‘T_(B)(j)’), and associated battery powers and power cost inputs areinput to a cost function 450, which executes to determine a power cost(‘Pcost(j)’) for operating the powertrain at the candidate input poweror candidate input torque and candidate input speed in response to theoperator torque request in the candidate operating range state. The 1-Dsearch engine 415 iteratively generates candidate input torques over therange of input torques and determines the power costs associatedtherewith to identify a preferred input torque (‘Ti*’) and associatedpreferred power cost (‘P*cost’). The preferred input torque (‘Ti*’)comprises the candidate input torque within the range of input torquesthat results in a minimum power cost of the candidate operating rangestate, i.e., the preferred power cost. The 2-D search engine 410iteratively generates the candidate input powers and candidate inputspeeds over the range of input speeds and range of input powers anddetermines the power costs associated therewith to identify a preferredinput power (‘Pi*’) and preferred input speed (‘Ni*’) and associatedpreferred cost (‘P*cost’). The preferred input power (‘Pi*’) andpreferred input speed (‘Ni*’) comprises the candidate input power andcandidate input speed that result in a minimum power cost for thecandidate operating range state.

FIG. 10 graphically illustrates the input speed determined withoutcompensating for inertial effects and a preferred input speed determinedwith compensating for inertial effect during transitions between G1 andM1. In this depiction, compensating for inertial effects increasespreferred input speed determinations for the fixed gear mode operatingrange states greater than preferred input speed determinations for themode operating range states. The preferred input speed determinationsaffect power of the engine 14, e.g., additional preferred input speedrequires additional engine power.

The additional power required to increase or decrease the engine inputspeed N_(I) affects power cost determinations (‘Pcost’) for eachoperating range state. When motor torques T_(A) and T_(B) are determinedbased upon the inertia effects resulting from inclusion of theacceleration terms {dot over (N)}_(I) and {dot over (N)}_(O) in theoptimization function 440 additional power required to increase ordecrease the engine input speed N_(I) is compensated in the power costdeterminations.

As depicted in FIG. 10, the additional power affects a trajectory of theinput speed N_(I) based upon the operating range state selection. Wheninertia is uncompensated, the power cost determinations do not accountfor the additional power required to increase or decrease the engineinput speed N_(I). The operating range state selection is based uponnon-preferred power cost determinations thereby resulting in atrajectory of the input speed N_(I) that is less efficient. As FIG. 10shows for an exemplary situation, inertia compensation increasesoperating time in M1 and decreases operating time in fixed gear modeoperating range state G1 based upon a higher calculated power cost foroperating in G1 thereby increasing the total powertrain systemefficiency.

The state stabilization and arbitration block 280 selects a preferredtransmission operating range state (‘Hybrid Range State Des’) whichpreferably is the transmission operating range state associated with theminimum preferred power cost for the allowed operating range statesoutput from the operating range state analyzer 260, taking into accountfactors related to arbitrating effects of changing the operating rangestate on the operation of the transmission to effect stable powertrainoperation. The preferred input speed (‘Ni_Des’) is the engine inputspeed associated with the preferred engine input comprising thepreferred engine input speed (‘Ni*’), the preferred engine input power(‘Pi*’), and the preferred engine input torque (‘Ti*’) that isresponsive to and preferably meets the operator torque request for theselected preferred operating range state.

It is understood that modifications are allowable within the scope ofthe disclosure. The disclosure has been described with specificreference to the preferred embodiments and modifications thereto.Further modifications and alterations may occur to others upon readingand understanding the specification. It is intended to include all suchmodifications and alterations insofar as they come within the scope ofthe disclosure.

1. Method for controlling a powertrain system including an enginecoupled to an input member of a transmission device including torquegenerating machines and an energy storage device connected thereto, thehybrid transmission operative to transfer power between the input memberand an output member and the torque generating machines and selectivelyoperative in one of a plurality of operating range states, the methodcomprising: monitoring an operator torque request and a rotational speedof the output member; determining inertial effects of the transmission;determining motor torque outputs from the torque generating machines andan input torque from the engine based upon the inertial effects; andselecting a preferred operating range state and a preferred input speedof the input member based upon the operator torque request and theinertial effects.
 2. The method of claim 1, wherein the inertial effectsof the transmission comprise: an inertial effect of the output memberthat is based upon the rotational speed of the output member and aninertial effect of the input member.
 3. The method of claim 1, furthercomprising determining the inertial effect of the input member for afixed gear operating range state based upon the inertial effect of theoutput member for the fixed gear mode operating range state.
 4. Themethod of claim 3, comprising determining the inertial effect of theinput member based upon the inertial effect of the output member andparametric values based upon hardware gear and shaft interconnectionsand the fixed gear mode operating range state.
 5. The method of claim 1,wherein the inertial effect of the output member comprises a change inthe output member speed over a predetermined elapsed time period.
 6. Themethod of claim 1, wherein the inertial effect of the output membercomprises a rotational acceleration of the output member and wherein theinertial effect of the input member comprises a rotational accelerationof the input member.
 7. The method of claim 1, further comprising:monitoring the input torque from the engine to the transmission;iteratively determining motor torques for the torque generating machinesbased upon the engine input torque, the inertial effects, and theoperating range state; determining a power cost for operating at each ofthe iteratively determined motor torques of the torque generatingmachines and the engine input torque for each operating range state;selecting a preferred power cost and corresponding desired engineoperating point based upon the costs for each of the operating rangestates; and selecting the preferred operating range state based upon thepreferred costs for the operating range states.
 8. The method of claim7, further comprising: iteratively determining motor torques for thetorque generating machines for a fixed gear mode operating range state;and determining a power cost for operating at each of the iterativelydetermined motor torques of the torque generating machines and theengine operating point comprising engine input torque for each of thefixed gear mode operating range states.
 9. The method of claim 7,wherein engine operating points comprise engine input speed and engineinput power, and further comprising: iteratively determining motortorques for the torque generating machines for a continuously variableoperating mode; and determining a cost for operating at each of theiteratively determined motor torques of the torque generating machinesand the engine input torque for each of the continuously variableoperating modes.
 10. The method of claim 9, further comprising:determining ranges of permissible input speeds and engine input power;executing a two-dimensional search engine to iteratively generateparametric values within the ranges of permissible input speeds andengine input power; determining motor torques for the torque generatingmachines based upon the generated parametric values and the operatingrange state; and identifying a preferred engine input power andpreferred motor torques effective to expend a minimum cost.
 11. Themethod of claim 10, further comprising controlling operation of theengine to achieve the preferred engine input power.
 12. The method ofclaim 10, comprising determining the motor torques for the torquegenerating machines based upon the following equation $\begin{bmatrix}T_{A} \\T_{B}\end{bmatrix} = {{\begin{bmatrix}a_{11} & a_{12} \\a_{21} & a_{22}\end{bmatrix}\begin{bmatrix}T_{I} \\T_{O}\end{bmatrix}} + {\begin{bmatrix}b_{11} & b_{12} \\b_{21} & b_{22}\end{bmatrix}\begin{bmatrix}N_{I} \\N_{O}\end{bmatrix}} + {\begin{bmatrix}c_{11} & c_{12} \\c_{21} & c_{22}\end{bmatrix}\begin{bmatrix}{\overset{.}{N}}_{I} \\{\overset{.}{N}}_{O}\end{bmatrix}}}$ wherein {dot over (N)}_(I) represents the rotationalacceleration of the input member, {dot over (N)}_(O) represents therotational acceleration of the output member, T_(A) represents motortorque for a first torque generating machine, T_(B) represents motortorque for a second torque generating machine, T_(I) represents engineinput torque to the transmission, T_(O) is the output torque out of thetransmission, N_(I) is the input speed, N_(O) is the output speed, anda₁₁, a₁₂, a₂₁, a₂₂, b₁₁, b₁₂, b₂₁, b₂₂ c₁₁, c₁₂, c₂₁, and c₂₂ are knownparametric values determined based upon hardware gear and shaftinterconnections.
 13. Method for controlling a powertrain systemincluding an engine coupled to an input member of an electro-mechanicaltransmission device including electric machines and an energy storagedevice connected thereto, the electro-mechanical transmission deviceoperative to transfer power between an input member and an output memberand the electric machines and selectively operative in one of aplurality of operating range states, the method comprising: monitoringan operator torque request and a rotational speed of the output member;determining an inertial effect of the output member based upon therotational speed of the output member; determining an inertial effect ofthe input member; determining motor torque outputs from the electricalmachines and an engine based upon the inertial effects; and selecting apreferred operating range state based upon the operator torque requestand the inertial effects.
 14. The method of claim 13, further comprisingdetermining the inertial effect of the input member for fixed gearoperating range states based upon the inertial effect of the outputmember, parametric values based upon hardware gear and shaftinterconnections and the fixed gear mode operating range state.
 15. Themethod of claim 13, wherein the inertial effect of the output membercomprises a change in the output member speed over a predeterminedelapsed time period.
 16. The method of claim 13, wherein the inertialeffect of the output member comprises a rotational acceleration of theoutput member and wherein the inertial effect of the input membercomprises a rotational acceleration of the input member.
 17. The methodof claim 13, further comprising: monitoring an engine input torque tothe transmission; iteratively determining motor torques for the electricmachines based upon the engine input torque, the inertial effects, andthe operating range state; determining a cost for operating at each ofthe iteratively determined motor torques of the electric machines andthe engine input torque for each operating range state; selecting apreferred cost and corresponding desired operating points based upon thecosts for each of the operating range states; and selecting thepreferred operating range state based upon the preferred costs for theoperating range states.
 18. Method for controlling a powertrain systemincluding an engine coupled to an input member of an electro-mechanicaltransmission device including electric machines and an energy storagedevice connected thereto, the electro-mechanical transmission deviceoperative to transfer power between an input member and an output memberand the electric machines and selectively operative in one of aplurality of operating range states, the method comprising: monitoringan operator torque request and a rotational speed of the output member;determining an inertial effect of the output member based upon therotational speed of the output member; determining an inertial effect ofthe input member; determining motor torque outputs from the electricalmachines and an engine based upon the inertial effects; and selecting apreferred input speed from the engine to the transmission based upon theoperator torque request and the inertial effects.
 19. The method ofclaim 18, further comprising determining the inertial effect of theinput member for fixed gear operating range states based upon theinertial effect of the output member, parametric values based uponhardware gear and shaft interconnections and the fixed gear modeoperating range state.
 20. The method of claim 18, wherein the inertialeffect of the output member comprises a change in the output memberspeed over a predetermined elapsed time period.
 21. The method of claim18, wherein the inertial effect of the output member comprises arotational acceleration of the output member and wherein the inertialeffect of the input member comprises a rotational acceleration of theinput member.